Air carrier misinterprets clearance has altitude deviation and conflict.

Attributes
ACN	183518
Time
Date	199107
Day	Thu
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : tlh
State Reference	FL
Altitude	msl bound lower : 32000 msl bound upper : 32500
Environment
Flight Conditions	IMC
Light	Daylight
Aircraft 1
Controlling Facilities	artcc : zjx
Operator	common carrier : air carrier
Make Model Name	Widebody, Low Wing, 2 Turbojet Eng
Navigation In Use	Other Other
Flight Phase	climbout : intermediate altitude
Flight Plan	IFR
Aircraft 2
Operator	common carrier : air carrier
Make Model Name	Any Unknown or Unlisted Aircraft Manufacturer
Flight Phase	cruise other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : atp
Experience	flight time last 90 days : 215 flight time total : 3500 flight time type : 450
ASRS Report	183518
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : private pilot : commercial pilot : instrument pilot : atp
Experience	flight time last 90 days : 75 flight time total : 16000 flight time type : 700
ASRS Report	183526
Events
Anomaly	altitude deviation : overshoot conflict : airborne less severe non adherence : clearance other anomaly other
Independent Detector	other controllera
Resolutory Action	other
Consequence	faa : reviewed incident with flight crew
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

I was flying an air carrier a widebody transport from mco to lax. During the climb to altitude we were given FL310 due to traffic, FL350 was our requested altitude. Our altitude was then changed to what we heard was FL330 which was put in the mode control panel, and started a 'VNAV' climb on autoplt. When passing FL325 center gave us a call and told us to descend to FL320 where he had cleared us. He had stated that he got a 'conflict alert' from us with an air carrier B aircraft which was at FL340. In discussing the event, we (captain and I) thought that we were cleared to FL330. I have never been assigned a nonstandard altitude such as FL320. Center told us that they have done that before, i.e., 2 aircraft requesting FL330 so they put one at FL340 and the other at FL320. I have never heard of, or been cleared like that before, the air carrier B jet commented to the unusual situation. Since pilots are taught to fly by the rules I feel that this nonstandard clearance may have been misinterpreted. Pilots are also flexible as controllers are but when such a nonstandard clearance is issued it should be stated and emphasized clearly what it is and why he is doing it.

Original NASA ASRS Text

Title: ACR MISINTERPRETS CLRNC HAS ALT DEV AND CONFLICT.

Narrative: I WAS FLYING AN ACR A WDB FROM MCO TO LAX. DURING THE CLB TO ALT WE WERE GIVEN FL310 DUE TO TFC, FL350 WAS OUR REQUESTED ALT. OUR ALT WAS THEN CHANGED TO WHAT WE HEARD WAS FL330 WHICH WAS PUT IN THE MODE CTL PANEL, AND STARTED A 'VNAV' CLB ON AUTOPLT. WHEN PASSING FL325 CENTER GAVE US A CALL AND TOLD US TO DSND TO FL320 WHERE HE HAD CLRED US. HE HAD STATED THAT HE GOT A 'CONFLICT ALERT' FROM US WITH AN ACR B ACFT WHICH WAS AT FL340. IN DISCUSSING THE EVENT, WE (CAPT AND I) THOUGHT THAT WE WERE CLRED TO FL330. I HAVE NEVER BEEN ASSIGNED A NONSTANDARD ALT SUCH AS FL320. CENTER TOLD US THAT THEY HAVE DONE THAT BEFORE, I.E., 2 ACFT REQUESTING FL330 SO THEY PUT ONE AT FL340 AND THE OTHER AT FL320. I HAVE NEVER HEARD OF, OR BEEN CLRED LIKE THAT BEFORE, THE ACR B JET COMMENTED TO THE UNUSUAL SITUATION. SINCE PLTS ARE TAUGHT TO FLY BY THE RULES I FEEL THAT THIS NONSTANDARD CLRNC MAY HAVE BEEN MISINTERPRETED. PLTS ARE ALSO FLEXIBLE AS CTLRS ARE BUT WHEN SUCH A NONSTANDARD CLRNC IS ISSUED IT SHOULD BE STATED AND EMPHASIZED CLEARLY WHAT IT IS AND WHY HE IS DOING IT.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.